For our entertainment this weekend, Paul Bettany will be waging his own personal battle between heaven and earth.

The handsome Brit’s image as the assault-rifle-toting archangel Michael in the doomsday fantasy “Legion” has been inescapable of late. In the intelligent, emotional “Creation,” meanwhile, he plays Charles Darwin over a span of crucial years. As Bettany raids a hotel suite’s mini-bar for a vodka tonic, he delights in the irony of simultaneously manifesting as an angel and as the man who, as one “Creation” character says, “killed God.”

“I was making ‘Legion’ and the script for ‘Creation’ came up — it was written by [director] Jon Amiel and John Collee, who’s a great writer, he wrote ‘Master and Commander.’ I had been reading Darwin’s diaries from the Beagle when I was making ‘Master and Commander’ as research [for his Darwinesque character, Dr. Stephen Maturin], and I had been interested in playing him,” he says. “I loved the script, and I thought it would be really fun, going from a big action movie to this small, heartfelt movie about something I care deeply about.”

Bettany’s immense respect for Darwin made him reluctant to judge his own performance.

“I don’t know if I was successful; that will be for other people to decide. I’m a glass-is-half-empty kind of human being — I’m already thinking about the next vodka tonic,” he says, punctuating the riff with a tap of the literally half-empty glass.

“I kept thinking, how am I going to produce a human being who has arguably the greatest single idea that any human being has ever had? And I slowly realized I couldn’t. Because he was the grandfather of evolution and I’m an actor. But I do know about loss and madness. Those are the things I share in common with Charles Darwin. I know what it feels like to lose people.”

The film, expanding into wider release on Friday, is less about the revolutionary theory itself than the naturalist’s decision, after 20 years, to share his findings with the world.

“There are a lot of reasons for that procrastination we can guess at, and one is the death of their child,” Bettany says. “His wife was a fervent Christian and got an incredible amount of solace from the idea of heaven and God being there, and that they would all meet again. And he’s about to potentially rob her of that solace.”

To play a celestial creature in “Legion,” opening Friday, Bettany could seek only earthly references.“It’s a similar problem in that I can’t be an angel. Ask my wife,” archly adds the husband of actress Jennifer Connelly, who plays Darwin’s wife in “Creation.”

“I can’t interview an angel and say, ‘What’s it like?’ So I went to museums. What I noticed about angels, often they have swords and spears, and they’re ripped,” he says, laughing. “I mean, actually, all we’re doing is changing the weapon — he’s got an M-16. What I need to do is go to the gymnasium. In postproduction they’re going to put 8-foot wings on me, and I can get on with the sort of human bit, which is fun.”

His archangel Michael joins forces with mankind after God, having lost all hope for humanity, sends in his angels to bring on the apocalypse.

“He has the courage of his convictions. Now to defy your boss in any walk of life is a traumatic, frightening and courageous thing to do. But when your boss is God…”

The multiple-award-winning actor gets no vertigo when fluttering from the lofty goals of art films to what some might sniff at as the lower aims of genre movies.

“I love all sorts of movies. I love ‘All Quiet on the Western Front,’ I love ‘Battleship Potemkin,’ I love ‘Brief Encounter.’ But I also love ‘Dawn of the Dead’ and ‘Night of the Living Dead,’ and I’d be lying if I tried to cover that up and pretend I had more sort of educated tastes.

“I don’t want people to go to ‘Creation’ and eat popcorn throughout, but I absolutely want to go to ‘Legion’ and see people’s popcorn go up in the air when they get scared.”